Oof, I’ve been in a very similar situation before — merging catalogues can get messy real quick, especially if you forget you’ve done it already.
I had a ton of duplicates (and even triplicates) too, and my main concern was not losing the edited versions. I used a tool called Duplicate Photos Fixer Pro — it helped me scan the entire catalogue folder and find duplicates based on content, not just file names. What’s nice is that it gives you a preview, so you can manually review and avoid deleting any images that have edits or metadata changes.
It was a lifesaver, especially since starting over wasn’t an option. Might be worth giving it a shot! Maybe this Guide can help you https://www.systweak.com/blogs/delete-du...